Temperature controlling device



June 18, 1935.

A. H. HEYROTH TEMPERATURE CONTROLLING DEVICE Filed Jan. 27, 1932 2Sheets-Sheet 1 F511 is INVENTOR ALBERT H. HEYROTH ATTORNEY June 18,1935. A H, EY TH 2,005,584

TEMPERATURE CONTROLLING DEVICE Filed Jan. 2'7, 1932 2 Sheets-Sheet 2 ZINVENTOR ALBERT H. HEYROTH BY W0 ATTORNEY Patented June 18, 1935 UNITEDSTATES 2,005,584 TEMPERATURE CONTROLLING DEVICE Albert H. Heyroth,Niagara Falls, N. Y., assignor to Globar Corporation, Niagara Falls, N.Y.

Application January 27,1932, Serial No. 589,177

6 Claims.

The invention relates to an electric current control system whereby theratio of the alt to the on periods may be varied to control the energyin the heat producing apparatus.

The invention is particularly adapted for the heat regulation inelectric household appliances and will be explained for such use.

The ordinary arrangement for controlling temperature in electric heatingappliances is by means of a plurality of circuits which are switchedinto various combinations as series, series parallel, or parallel. Sucha system limits the number of temperatures possible with a resultinguneconomical operation of the heating appliance.

An object of this invention is to provide a flexible temperaturecontroller for heat producing apparatus by including in the main circuitof the apparatus a make and break switch controlled by athermo-responsive device. The present invention relates to improvementsin a control device of this kind and essentially consists in aparticular physical arrangement having certain practical advantages.

The invention will be more fully described with reference to theaccompanying drawings:

Figure 1 is a bottom plan view of a control switch constructed inaccordance with the present invention;

Figure 2 is an elevation of my control mechanism looking in thedirection of the arrow A of Figure 1, the adjacent face of the casingand the upper part of the frame being removed;

Figure 3 is a view taken in the direction of the arrow B of Figure 1,the adjacent part of the casing being removed; v

Figure 4 is a view taken in the direction of the arrow C of Figure 1,the adjacent part of the casing being removed;

Figure 5 is a schematic circuit diagram of the temperature controlsystem of this invention;

Figure 6 is a plan view of the rear of the control rheostat;

Figure 7 is a plan view of the frontof the control rheostat;

Figure 8 is a section of the control rheostat;

Figure 9 is a conventional view of the control panel; and

Figure 10 illustrates a method of mounting the control rheostat ofFigure 8.

To facilitate an understanding of the mechanism illustratedin Figures1-4, 6-9 and of the manner in which it operates, I will first follow theschematic circuit as shown in Figure 5-.

The reference characters I, 2, 3, 4 designatethe outlet points of theswitching mechanism which is enclosed within case 22, Figure 2. Thereference character 5 of Figure 5 indicates the controlled appliance.The reference characters 8 and I5 designate the power leads. Thecontacts 6, l and 2| are incorporated in the control rheo- 5 stat shownin Figures'l, 8 and 9.

The operation of my invention is as follows:

When the contact arm 6 is moved from the off position (shown in theschematic circuit diagram of Figure 5) to the position marked 10 low oranywhere between the position marked low and the position marked high,points I and 2 will be connected through contact arm 6 and rail 1. Thecurrent will then flow from the service line 8 through point 3, heatingcoil 9', 15 point 2, contact arm 6, rail 1, point I, bimetal thermostatelement II), contact II, wire I2, solenoid I3, wire I4, point 4, throughelement 5 to the service line I5. Since the winding of the solenoid I3has a relatively very high ohmic re- 20 sistance, the current is limitedto a very small value and does not, at this stage, serve any purposewith respect to the controlled appliance 5. It is suflicient, however,to energize solenoid I3 and to cause it to draw contact arm I6 intoelec- 25 trical contact with contact I! against the compression ofspring I8. In doing so, the operation of the mechanism is such thatcontact I6 does not engage contact I1 until after I6 has passed thelatching position with respect to latch I9. 30 The engagement of I6 andI 1 short circuits the winding of solenoid I3 in that it joins wire I4(one terminal of the solenoid winding) to wire I2 (the other terminal ofthe solenoid winding) by means of the following connections: lead wire35 I4, contact I'I-I6, wire 20, point 2, contact arm 6, rail I, point I,bimetal I0, contact H, and lead wire I2. The current in the solenoid I3is thereby diminished and the spring I8 will tend to carry contact armI6 to its initial position. However, since I6 has been carried beyondthe latching position with respect to I9, as stated above, I6 can onlymake a slight return movement before it is stopped by its engagementwith the latch on arm I9. It is to be noted that the mech- 45 anism isso constructed that the contact between I! and I6 is not lost duringthis movement. Contacts I6 and I! not only serve to deenergize solenoidI3 as described, but also constitute the main switch contacts withrespect to appliance 5. The 50 operating current for appliance 5 willnow flow through the system as follows: service line 8, point 3, heatingcoil 9, wire ZIL-contact I6-I1, wire I4, point 4, appliance 5 andservice line I5.

It is assumed at this state that the contact 55 arm 6 is at the positiondesignated as low, in which position contact between 6 and l isestablished, but contact between 8 and 2i is open. At this setting ofcontact arm 5 all of the current flowing through controlled appliance 5will pass through the heating coil 9. Heating coil a is therefore now atits highest heating effective ness. The heating coil 9 is in such aposition with respect to the bimetal ill that a maximum amount of energyradiated from. heating coil :3 will be absorbed by the material ofbimetal ill. It is to be noted that the heating coil 9 may be of suchresistance as to be no appreciable factor in the overall resistance ofthis circuit. Moreover, the energy dissipated by heating coil 9 at thisstage is so low in value that it constitutes a negligible loss withrespect to the capacity of the controlled appliance 5. The function ofthe heating coil 9 is to warm the bimetal l and cause it to flex in thedirection indicated by the dotted line immediately above, which dottedline designates the unlatching position. The bimetal l l in flexingopens the contact between ill and M. It is to be noted that contacts illand ii are in a branch short line containing the solenoid 93 by virtueof the engagement of i6 and ill. Therefore, very little current isflowing through the solenoid and no spark will result from the openingof contact in and l l through the flexing of bimetal ill. The flexing ofbimetal ill through its mechanical engagement with latch ill will tendto raise 99 to the unlatching position. At the unlatching position, thecontact arm i6 is released from its engagement with latch l9 therebypermitting the spring IE to return contact arm is to its initialposition out of engagement with contact ii, the contact lS-ll being, asstated above, the main switch contact with respect to the controlledappliance 5, the opening of contact Iii-ll opens the operating circuitof appliance 5.

The sequence of events just described may be designated as those takingplace during the on period of appliance 5. Hence, during the timerequired to flex bimetal Hi from its contact position with respect to H,to its unlatching position with respect to arm IS, the appliance hasbeen receiving energy at its full rated capacity; that is, appliance 5has been directly across service lines 8-l5.

The sequence of events now to be described may be designated as the oilperiod with respect to appliance 5, since during this period thecontacts l6l'l are out of engagement and the appliance 5 is in opencircuit position.

The contacts l6l'l being open, heating coil 9, as well as appliance 5,is deprived of current. The bimetal l0 istherefore free to cool andreturn from the flexed or unlatching position to its normal position inengagement with contact II.

The off period with respect to appliance 5.

therefore, embraces the interval of time required for bimetal Ill toreturn from the unlatching or flexed position to its normal contactingposition with respect to II.

Figures 2 and 3 show the application of my invention in a commercialform. The same numbers for designating corresponding parts are used inthese figures as are used in the schematic circuit diagram Figure 5.

The drawings show the manner of housing by means of the shell 22. Theprongs I, 2, 3, 4 which extend through the housing correspond to pointsI, 2, 3, 4 on the schematic diagram. To render it impossible to plug theassembly into a socket in any but the correct manner, one of the fourprongs is made smaller in diameter than the other three. Another methodof accomplishing the same result is by disposing them asymmetrically sothat they can only be inserted into the holes of the socket in thecorrect manner.

The frame 23 is a sheet iron stamping which forms a magnetic yoke aroundthe solenoid it, and its extensions above the solenoid it serve as themounting frame or support for the bimetal iii, contact arm it, latch i9,contact ii, and also provide support for springs i tl8 and the guideslots for stamping 26, which carries the solenoid plunger 26. The frame"23 also provides an anvil within the solenoid in that a button Si isformed on its lower cross member, which button forms a plug whichextends upward into winding l? and toward which plunger 26 is drawn whenthe solenoid i3 is energized. ihis button or anvil Si is indicated indotted lines in Figure 2 of the drawings.

The assembly ll-2 l-2526 constitutes the moving element of the switch.is an iron plunger, one end of which projects slightly into the solenoidit, as shown in Figure 2 of the drawings, and to the other end of whichis fastened the stamping Referring to Figure 4 of the drawings, thestamping 2&1 is shaped so that its lower cross member extends throughthe guide slots in 23 and is provided with a hole at each end. Theseholes serve as eyelets in which springs lt-HSA are hooked.

The stamping 2 5 carries on its upper cross member the main switchcontact it which is insulated from 2 1 by means of insulating shim 25.The slot between the upper and lower cross arms of 2d guides the contactarm it, which is actuated by the movement of 24. The latching member ofthe contact arm 96 extends from the hinge pin of it through the slotbetween the upper and lower cross arms of 24, as shown in Figure 2 ofthe drawings.

The operation of the switch mechanism is as follows: when the winding I3is energized by the manual movement of the control (see Figure 3) fromoff to low, the plunger 26 is drawn downward toward the anvil 3| formedat 23 and situated within the lower end of the solenoid l3. The plunger26 carries with it the members 24. 25, I1, thereby stretching thesprings l8, |8A which connect the stationary frame 23 and moving element24. Since the contact I! is part of the assembly I1, 24, 25, 26, it willfollow the straight line downward movement of 26. cross-arm member 24moves downward, it engages the latching member of contact l6 causing itto rotate on its hinge pin 32. This movement brings the contacts l6 andI1 into engagement. Through the closing of contacts I 6 and H, thesolenoid I3 is deenergized. and with the opening of the contact H by theflexing of the bi-metal away from its contacting position, the solenoidcircuit becomes disconnected. As no curre t flows through the solenoidduring the on period after the closing of the main switch, the plunger26 can eventually return to its initial position when permitted by themember l9. After a slight movement in this direction, the latchingmember of contact l6 encounters the latch I 9 which stops furthermovement. Here it remains until bimetal IO has been heated sufficientlyto flex it outwardly, whereupon the latching member of contact I6 isreleased from engagement with IS.

As the The springs |8--|8A are then free to return the assembly I1, 24,25, 26 to its initial open position.

The last phase of the operating cycle is the time interval required forthe bimetal III to return from its flexed (or unlatching) position, backto its contacting position with respect to contact I.

In order to explain the manner in which any temperature control may beobtained in the heating appliance, reference to Figures 6, 7, 8, 9 and10 will be necessary.

A complete control is effected through the movement of contact arm 6from the off position to the high position or vice versa. Referring toFigure 5, it is obvious that, as the outer end of the arm 6 is movedalong the slide wire resistance 2| toward the high position, the part ofthe total current (from the line wire 8) which flows through theresistance 2| will increase, and that the part which flows through theheating coil 9 will decrease.- Hence, the movement of the contact arm 6toward the high position has the efiect of increasing the on interval ofthe appliance 5 within the operating cycle with a consequent increase ofthe resultant temperature of the appliance 5. Incidentally, during themovement of the contact arm 6, the oil period of the operating cycle isshortened for the reason that the diminishing radiation from the heatingcoil 9 diminishes the tendency to move the bimetal III to the unlatchingposition. Hence, the on period is increased and the of! perioddecreased. A co'nverse effect is produced by moving 6 toward the ofiposition. It is tobe noted that the range of control with respect toappliance 5 includes the two extremes--off position and high position.At the off position the solenoid I3 is inoperative in its open circuitposition (|6 being open) due to the interruption of its circuit at thecontact 6'|. The appliance 5 therefore remains definitely inoperative aslong as the contact arm 6 is in the off position. At the other extreme,when contact arm 6 is in the high position, solenoid I3 is inoperativein its closed circuit position (|6|'I being closed) due to the fact thatits winding is short circuited by the engagement of |6|1. At thisposition of contact arm 6, the engagement of IS with IT is maintainedbecause bimetal H], as described above, will not actuate latch l9 due tothe short circuiting of heat coil 9. It is evident that the contact arm6 may be adjusted between these extremes to a position which will efiectthe required resultant temperature of appliance 5. It is also evidentthat the assembly comprising 6, 1 and 2| is exceedingly simple andinexpensive and that this assembly may be remote from the switchingmechanism enclosed in the dotted line.

For example, just as appliance 5 may be remote from the balance of thecircuit by lengthening the lead from it to point 4 as required, theassembly 6, I, 2| may be remote from the switching mechanism proper bylengthening, to the required degree, its leads to points 2 and 3. I

In the particular mechanism, as for example devised for operation withdomestic electric ranges, 6, 1, 2| are mounted on an insulating disc 2in diameter and A" thick. This assembly is mounted in the rear of therange switch panel with the shaft of arm 6 extending through the paneland terminating in front of the panel in a knob with an index fingersimilar to the knobs employed in volume control rheostats in radiopractice. The front of the panel Figure 9 is marked high, low and offand has a series of calibration marks between the low position and thehigh position so that the operator can readily set the index finger ofthe knob in the position required for the purpose at hand.

I claim:

1. A system for varying the ratio of the on and off periods of anintermittently operated electrical device, comprising in combination anelectromagnetic switch actuated in one direction by a solenoid and inthe reverse direction by mechanical means, holding means for preventingthe return movement of the switch after it has been actuated by thesolenoid, a mechanical release means adapted to disengage the saidholding means, a thermoresponsive element operating between twopositions, the thermoresponsive element in one of the said positionsmaking an electrical contact which closes the solenoid circuit and inthe other of the said positions actuating the mechanical release topermit the automatic opening of the switch, a shunt circuit by-passingat least a portion of the current around the solenoid when the saidswitch is closed, means for applying heat to the thermoresponsiveelement in repetitive cycles dependent upon the on and ofi positions ofthe switch, and means for varying the rate of heat supply to thethermoresponsive element.

2. In a mechanism for controlling the on and ofi periods of anelectrical device, a magnetic switch actuated by a solenoid, holdingmeans for retaining the said switch in closed position, a mechanicalrelease'means which permits the mechanical opening of the switch,mechanical means for opening the switch when the release is actuated, abi-metal strip operating between two positions, the bi-metal strip inone of the said positions making an electrical contact which closes thesolenoid circuit and in the other 'of the said positions actuating thesaid release, a shunt circuit closed by the said switch, the said shuntcircuit passing through the bi-metal contact and deenergizing thesolenoid when the bi-metal contact and the switch are closed, and asecond shunt circuit also closed by the said switch which contains aheating element for the bi-metal strip and which by-passes the currentaround the contact made by the bi-metal strip when the said contact isopen and the magnetic switch is closed.

3. In a mechanism for controlling the on and off periods of anintermittently operated electrical device, a magnetic switch actuated bya solenoid, a. holding means adapted to maintain the switch in a closedposition, a spring adapted to open the switch when the said holdingmeans is disengaged, a bi-metal strip operating between two positions,the bi-metal strip in one of the said positions making an electricalcontact which closes the solenoid circuit and in the other of the saidpositions disengaging the said holding means, an electric heatingelement in close proximity to the bi-metal strip and adapted to impartheat thereto, a circuit for the said heating element which isalternately opened and closed with the opening and closing of the saidswitch, and a shunt circuit closed by the said switch, the shunt circuitby-passing the current around the solenoid and de-energizing thesolenoid when the' circuit for the device being controlled is closed. 4.The combination described in claim 3, in which the contact closing thesolenoid circuit is rigidly attached to the bi-metal strip.

5. The combination described in claim 3, in

which a shunt circuit also by-passes the current around the contactclosed by the bi-metal strip when the solenoid circuit is closed.

6. In a mechanism for controlling the on and 01? periods of anintermittently operated electrical device, a solenoid, a plungeractuated by the solenoid, a contact carried by the plunger and adaptedto close the electrical circuit of the device being controlled,mechanical holding means for maintaining the plunger in a fixed positionafter actuation of the solenoid, mechanical means for moving the plungerin a direction opposite to the direction of movement produced by thesolenoid when the said holding means is disengaged,

a bi-metal strip operating between two positions,

aooasee the bi-metal strip in one of the said positions making anelectrical contact which closes the solenoid circuit and in the other ofthe said positions disengaging the said holding means, an electricheating element in close proximity to the bi-metal strip and adapted toimpart heat thereto, a circuit for the said heating element which isalternately opened and closed with the opening and closing of the saidswitch, and a shunt circuit closed by the said switch, the said shuntcircuit by-passing the current around the solenoid and de-energizing thesolenoid when the circuit for the device being controlled is closed.

ALBERT H. .HTEYROTH.

